The present disclosure relates to midair retrieval technology. More specifically, it relates to an aerodynamically controlled grapple assembly (hereafter sometimes referred to as the Aero-Grapple) which can be employed during midair retrieval operations.
Midair retrieval is a technique used to capture an object while it is still airborne. The object to be retrieved is slowed by means of one or more parachutes, and a specially equipped aircraft, more particularly a helicopter, matches the object's trajectory and catches it in midair. Successful midair retrieval techniques require favorable atmospheric conditions, a successful execution of maneuvers to bring a grappling hook mounted beneath the retrieving helicopter into the correct position, and the correct operation of the retrieval helicopter itself. Helicopters are the optimal aircraft for these operations, due to their Vertical Takeoff and Landing (VTOL) capability.
It has been determined that for midair retrieval, the use of a parafoil is advantageous in comparison to a parachute, in order to more easily engage the object to be retrieved. A parafoil has numerous advantages over a non-gliding “round” parachute, all of which contribute to a far greater margin of safety as compared with legacy midair retrieval techniques. The forward glide of a parafoil enables a helicopter to approach and engage the object to be retrieved with a lower separation velocity than is possible with a round parachute. A parafoil does not have a large low-pressure area above it. This allows the helicopter to fly directly over the parafoil without fear of an uncommanded descent into the parafoil. If maneuvering to the same proximity were attempted over a round parachute, the helicopter would experience a rapid onset of “settling with power” as a result of hovering in the entrained down-flow present above the round parachute, likely causing a midair collision with the round parachute. In addition, a parafoil generates a lower rate of descent for a given weight and provides a better sight picture for the retrieving pilot.
The state of the art in midair retrieval is exemplified by U.S. Pat. No. 6,824,102 dated Nov. 30, 2004. The subject matter of that patent is incorporated herein by reference in its entirety. One problem with the known midair retrieval system is that the hook or grapple currently employed is not aerodynamically configured. Therefore, it cannot be controlled. Various forms of hooks and grapples are known, including latching and remotely activated types. However, the known grapple which is suspended below a helicopter will swing in an uncontrolled pendular motion. This motion can be damped through aggressive precision control inputs by the pilot of the capture helicopter, but it greatly increases the time required to capture a parafoil-borne payload.
Control of the Aero-Grapple by a trained flight crew member residing in the retrieval helicopter would be advantageous in order to allow the retrieval helicopter to more easily capture payloads carried by a descending parafoil, parachute, or the like. It would be desirable to improve the safety and reliability of an in-flight grapple engagement. To this end, it would be desirable to utilize lifting surfaces with aerodynamic controls integrated with the remote grapple mechanism in order to control the position of the Aero-Grapple independent of helicopter motion.
Accordingly, it has been considered desirable to develop a new and improved aerodynamic retrieval assembly, or Aero-Grapple, which meets the above stated needs and overcomes the foregoing difficulties as well as others, while providing better and more advantageous overall results.